MPEG Layer-3 Codec Update

[Arminius]

Ten years after they were released Microsoft decided to update l3codeca.acm and l3codecx.ax because of a security vulnerability rated as "critical".

http://support.microsoft.com/kb/977816/en-us

http://www.microsoft.com/technet/security/bulletin/MS10-026.mspx

I downloaded the update for Win2000 and it was a simple matter of extracting the contents of the installer and copying the new codecs to the WINDOWS\SYSTEM folder in 98SE. They work as they should from what I can tell.

Download page:

http://www.microsoft.com/downloads/details.aspx?familyid=F6394FC2-B9D0-46CF-9265-A0D4AEB1448F

The old version of l3codecx.ax I had installed was 1,5,0,50 with the timestamp 1-May-2002 18:51:36. The new version is 1,6,0,51. Updating WinME may be a little trickier as the version number of l3codecx.ax that shipped with it is 1,9,0,0311 for some reason.

The updated l3codeca.acm is a straight forward point upgrade. The new version 1,9,0,0306 replacing the old 1,9,0,0305.

No word on whether l3codecp.acm v 3,3,2,44 which so many people have installed on their system has a similar security flaw.

[CharlesF]

Same thing here. Running well.

I had l3codecx.ax version 1,5,0,50 timestamped 12-Dec-2002

and l3codeca.acm version 1,9,0,0305 from 3-Oct-2008 (!?)

I have also the l3codecp.acm version 3,3,2,44 timestamped 28-Jan-2005,

from Unofficial WMP10 XP MP3 Codec L3CODECP.ACM 3.3.2.44 for WMP 7/8/9

which is not present in the MS patch.

[Prozactive]

Thanks for the information. Is there a good way to test and verify that the updated files work properly?

BTW, my existing files were also:

l3codecx.ax

12-Dec-2002, 12:14:32 AM, 83,456 bytes, version 1,5,0,50

l3codeca.acm

03-Oct-2008, 2:42:10 AM, 290,816 bytes, version 1,9,0,0305

I believe the 03-Oct-2008 version of l3codeca.acm came from the latest version of MP9URP9X.

Edited May 1, 2010 by Prozactive

[CharlesF]

No word on whether l3codecp.acm v 3,3,2,44 which so many people have installed on their system has a similar security flaw.

Read here: Microsoft Security Bulletin MS10-026

The security update addresses the vulnerability by correcting the way that the Microsoft MPEG Layer-3 audio codecs decode the MPEG Layer-3 audio stream in specially crafted AVI files.

...

Vulnerability Information: MPEG Layer-3 Audio Decoder Stack Overflow Vulnerability - CVE-2010-0480

l3codeca.acm & L3CODECX.AX are MP3 decoders

L3CODECP.ACM is the encoder.

[Arminius]

l3codeca.acm & L3CODECX.AX are MP3 decoders

L3CODECP.ACM is the encoder.

L3codeca.acm and l3codecp.acm are both encoder/decoders. L3codeca.acm is the "advanced" version which can only encode up to 56kbps, and l3codecp.acm is the "professional" version which can encode all the way up to 320kbps.

Depending on the entries in the SYSTEM.INI file, if you have l3codecp.acm installed your system might not utilize l3codeca.acm at all.

True, l3codecx.ax is a decoder only.

[PROBLEMCHYLD]

How do I register these 2 files?

L3CODECA.ACM

L3CODECX.AX

[CharlesF]

How do I register these 2 files?

L3CODECA.ACM

L3CODECX.AX

They are supposed to already exist in your %WINDIR%\SYSTEM directory (usually C:\WINDOWS\SYSTEM).

If so, you only have to replace them by the new version (no reboot or registration required) .

[PROBLEMCHYLD]

They are not though. So please tell me the next step. Thank you

[Arminius]

They are not though. So please tell me the next step. Thank you

CharlesF is correct. It is a straight forward file replacement. The odds are you have them installed on your system. If the new files don't work then you have bigger problems.

Some info:

L3CODECX.AX is native to Win98. It should be there and working unless you don't have any version of WMP installed at all (including the one that came with Win98).

The story behind L3CODECA.ACM is more complicated.

Originally L3CODECA.ACM was installed as part of the WMFDIST.EXE, later it was also included with WMP7 and WMP9. For Win98 to recognize L3CODECA.ACM it requires the following entry in the SYSTEM.INI file in the [drivers32] section:

msacm.l3acm=l3codeca.acm

There is (was) a separate entry for L3CODECP.ACM :

msacm.l3codec=l3codecp.acm

With both entries both codecs are available to third party encoder front ends like CDex.

The WMP6.4 installer is annoying because it deletes L3CODECP.ACM and removes the entry from the SYSTEM.INI file if it finds it on your system. A lame attempt by MS to remove the Radium codec from peoples systems? Or the old L3CODECP.ACM v1,0,0,48 which could only encode as high as 128kbps ??

The WMP7 installer has a different strategy. If it finds L3CODECP.ACM on your system L3CODECA.ACM will still be copied to the \WINDOWS\SYSTEM folder but the two above entries in the SYSTEM.INI file are replaced with a single entry:

msacm.l3acm=l3codecp.acm

L3CODECP.ACM becomes the codec used by WMP7 and third party apps that rely on it. L3CODECA.ACM resides on your system but goes unused.

Whether you have one entry or two in the SYSTEM.INI file depends on what you have installed and the order you installed them.

I can't say for sure what the WMP9 installer does if it finds L3CODECP.ACM on your system because I never ever installed it. My guess would be that it handles it the same way the WMP7 installer does. Once I moved from Win98FE to Win98SE I had enough of WMP7 bloat and Winamp 2's microscopic buttons so decided to use 1BY1 to play audio files. I use WMP6.4 and JetAudio to play everything else.

Edited May 2, 2010 by Arminius

[CharlesF]

They are not though. So please tell me the next step. Thank you

My 2 cents (but no guaranty):

you could try a clean reinstall of WMP9 from Microsoft: http://www.mdgx.com/wmp.htm#WMP9

then WMP9 Update Rollup Packs of erpdude8: http://www.mdgx.com/wmp.htm#URP

or 98MP10 of MDGx: http://www.mdgx.com/wmp.htm#98MP10, to get the last files released

and then Unofficial WMP10 XP MP3 Codec, that is providing the 'L3CODECP.ACM' file: http://www.mdgx.com/wmp.htm#L3C

at last, replace with the 2 new files

@Arminius:

I have just checked in my 'SYSTEM.INI' section [drivers32]

and found:

...

msacm.L3acm=L3CODECP.ACM

msacm.L3codec=L3CODECP.ACM

...

Is it useful to add a line: msacm.l3acm=l3codeca.acm, or not necessary?

[Arminius]

@Arminius:

I have just checked in my 'SYSTEM.INI' section [drivers32]

and found:

...

msacm.L3acm=L3CODECP.ACM

msacm.L3codec=L3CODECP.ACM

...

Is it useful to add a line: msacm.l3acm=l3codeca.acm, or not necessary?

That is what I call double indemnity.

Before the security update came out I would have said you can remove the line

msacm.L3codec=L3CODECP.ACM

and just have the one line

msacm.L3acm=L3CODECP.ACM

However, because of the security update I recommend you change the line

msacm.L3acm=L3CODECP.ACM

to

msacm.L3acm=L3CODECA.ACM

and keep the line

msacm.L3codec=L3CODECP.ACM

Don't add another line msacm.l3acm=L3CODECA.ACM

The line msacm.L3acm=L3CODECA.ACM should be higher in the list than

msacm.L3codec=L3CODECP.ACM

That will give L3CODECA.ACM a higher priority over L3CODECP.ACM as a decoder while still giving you access to the full range of bit rates when you want to use L3CODECP.ACM as an encoder.

Check this out:

Control Panel-->Multimedia-->Devices Tab-->Audio Compression Codecs-->

Click on individual codec entries and then "Properties" to view the priority of each codec.

[Offler]

I have just tested l3codex.ax ... Works well and i have confirmed that you need only to replace it in system directory.

From Media Player Classic you just need to play any *.mp3 file and check the Filter name "Mpeg Layer-3 Decoder". check the version before and after the update. Before update i had version 1.5 (build 50) and now its 1.6 (Build 51). Also most interesting should be link to Fraunhofer institute web

Edited May 2, 2010 by Offler

[CharlesF]

Thanks for this clear explanation.

[Arminius]

I played the avi's that came on the Windows 95 and 98 CDs using WMP6.4 and the new L3CODECX.AX and had no problem.

I tested L3CODECA.ACM as a decoder using 1BY1 Directory Player and MP3 Direct Cut, and as an encoder using CDex, Audiograbber, and the old FhG MPEG Layer-3 Producer. They worked fine except I just found out that FhG MPEG Layer-3 Producer only recognizes the first L3 ACM codec listed under [drivers32] in the SYSTEM.INI file and ignores entries lower down. It may be relevant to what I said earlier about encoder "priority" if other encoding apps have the same foible.

I don't expect any dramas with the new codecs. It seems that either they work or they don't, as was the case with L3CODECP.ACM v. 3,4,0,0 from WMP11 not being recognized on 9x systems.

[Prozactive]

I have just tested l3codex.ax ... Works well and i have confirmed that you need only to replace it in system directory.

From Media Player Classic you just need to play any *.mp3 file and check the Filter name "Mpeg Layer-3 Decoder". check the version before and after the update. Before update i had version 1.5 (build 50) and now its 1.6 (Build 51). Also most interesting should be link to Fraunhofer institute web

Oh duh.

I can't find the mp3 codec listed in WMP 9 but it seems to work fine.